The outcome of this research proposal revealed severe disturbances in both peripheral and central metabolism of the aromatic amino acid tyrosine and its decarboxylated metabolite, tyramine, in dogs following the construction of portacaval shunt. Furthermore, the degree of these metabolic abnormalities appeared to correlate with the deterioration of the physical and mental states of these dogs. A highly significant finding that has emerged from this research proposal is the severe impairment of central adrenergic function as exemplified by the pronounced depletion of brain dopamine and norepinephrine in shunted dogs as compared to sham operated dogs. This was followed by corresponding elevation of brain tyrosine and tyramine. A concomitant deficiency of brain catecholamines as well as an increase in CNS tyrosine and tyramine, could adversely affect brain function and thereby contribute to the encephalopathy of post-shunt liver disease.